Author Topic: Batch Sparge Theory  (Read 4651 times)

Offline richardt

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Batch Sparge Theory
« on: January 14, 2011, 12:44:07 PM »
I've read multiple posts on this forum as well as Denny's recent article about batch sparging. 

I get and agree with the whole "equal-concentration-of-sugars-throughout-the-mash" idea.

I have a hypothetical question regarding the lautering (or sparging) aspect of the process:

Assuming no change in temp, SG, wort composition, grist crush, etc., it seems that a larger drain surface area and/or shorter distance the wort must travel to get to the drain would be critical in terms of lautering (or sparging) speed.

What designs work best and why?  Has anyone ever tried a 3-D sparge manifold?  Why not?

I have a 10 gallon round Rubbermaid/Gott/Igloo cooler which can result in a grain bed of considerable vertical depth (e.g., up to the 8 gallon mark for high gravity beers using 25+ lbs of grain).  Lautering/sparging seems to take longer.  I suspect it has to do with grain bed compaction given its 12-18+ inch depth.

Hypothetically speaking, would a mildly domed 12-inch round SS false bottom with a 12-inch SS bazooka braid attached vertically help speed up batch sparging in a 10 gallon round cooler?

Offline denny

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Re: Batch Sparge Theory
« Reply #1 on: January 14, 2011, 12:53:47 PM »
Sorry to not really answer your question, but being the pragmatic type I am, switching to a rectangular cooler seems a much simpler solution.  But hypothetically, I'd guess you're correct.  But that's a difficult solution compared to a new cooler!
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Offline hokerer

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Re: Batch Sparge Theory
« Reply #2 on: January 14, 2011, 01:08:47 PM »
Hypothetically speaking, would a mildly domed 12-inch round SS false bottom with a 12-inch SS bazooka braid attached vertically help speed up batch sparging in a 10 gallon round cooler?

Theoretically, it would seem like that would speed things up.  Not sure about a 12-inch weenie sticking up into your mash, though - seems that could make stirring a bit of a problem
Joe

Offline richardt

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Re: Batch Sparge Theory
« Reply #3 on: January 14, 2011, 01:52:18 PM »
Yeah, Denny, you're right.  That would be the far more practical thing to do.
I do have a big rectangular cooler, ... but it is red (... big sigh :-\). 

Hoeker--you're also right. A "12-inch weenie" would probably get fractured or bent while stirring a stiff mash.

I does give me a different idea, though: Instead of the stiff bazooka screen what if there was a flexible SS hose braid (like what Denny uses) with the end crimped and a long string attached to the end of it.  Let it be flaccid during the mash and then pull it taut vertically when it is time to "perform" the lauter/sparge?

Sorry for the double entendres--it did start off as a legimate academic question...

Offline blatz

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Re: Batch Sparge Theory
« Reply #4 on: January 14, 2011, 02:11:12 PM »
*edit*

does the braid really get suction along the full length of the braid?

I don't think it does, which would make the length of the braid somewhat moot.

not sure entirely.
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Offline denny

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Re: Batch Sparge Theory
« Reply #5 on: January 14, 2011, 02:12:08 PM »
Look, I've gotta say that other than as a hypothetical exercise, this idea just isn't practical.  Why go to all that effort when you can just build a new cooler?
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Offline denny

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Re: Batch Sparge Theory
« Reply #6 on: January 14, 2011, 02:14:13 PM »
*edit*

does the braid really get suction along the full length of the braid?

I don't think it does, which would make the length of the braid somewhat moot.

not sure entirely.

I've experimented with this numerous times and the braid gets no "suction" at all.  That's why the length of braid doesn't really matter.  All the draining happens where the braid attaches to the outlet.  You can prove it by filling your (rectangular) cooler with water and lifting the braid out of the water as it drains.  No change in flow rate.
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Offline blatz

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Re: Batch Sparge Theory
« Reply #7 on: January 14, 2011, 02:17:46 PM »
*edit*

does the braid really get suction along the full length of the braid?

I don't think it does, which would make the length of the braid somewhat moot.

not sure entirely.

I've experimented with this numerous times and the braid gets no "suction" at all.  That's why the length of braid doesn't really matter.  All the draining happens where the braid attaches to the outlet.  You can prove it by filling your (rectangular) cooler with water and lifting the braid out of the water as it drains.  No change in flow rate.

that's what I was thinking - the braid acts as a filter, not a straw - the wort closest to the drain is being sucked out first - no different than if there were no braid at all.  I think a lot of people assume it is being sucked evenly along the braid like a manifold, which is not the case
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Offline Pawtucket Patriot

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Re: Batch Sparge Theory
« Reply #8 on: January 14, 2011, 02:55:18 PM »
Denny & blatz, that's exactly the reason I shortened the braid in cooler. And now I have the added benefit of not having an obstructive braid in the way when I'm stirring my mash!
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Offline euge

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Re: Batch Sparge Theory
« Reply #9 on: January 14, 2011, 03:23:31 PM »
*edit*

does the braid really get suction along the full length of the braid?

I don't think it does, which would make the length of the braid somewhat moot.

not sure entirely.

I've experimented with this numerous times and the braid gets no "suction" at all.  That's why the length of braid doesn't really matter.  All the draining happens where the braid attaches to the outlet.  You can prove it by filling your (rectangular) cooler with water and lifting the braid out of the water as it drains.  No change in flow rate.

Consider this- that while lifting the braid up doesn't alter flow rate because the max volume of fluid is exiting the drain restriction at any given moment until almost all the wort is gone.
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Offline tschmidlin

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Re: Batch Sparge Theory
« Reply #10 on: January 14, 2011, 03:34:02 PM »
Yes, as long as the maximum flow rate into the braid is faster than the flow rate out the end, raising the braid won't change it.  But if you reduce the available surface area too much with a tiny braid, a tiny mesh, or if it gets clogged, then it will alter the flow rate.  If clogging is a problem then having a longer braid will help because there will be more surface area for the wort to flow through.

But Denny has said in the past that he tested various lengths of braid and it makes no difference in his system, and based on the other thread he is crushing pretty fine, so I can't imagine you'd have any real issue.
Tom Schmidlin

Offline kerneldustjacket

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Re: Batch Sparge Theory
« Reply #11 on: January 14, 2011, 04:06:59 PM »
I recently started doing no-sparge batches, and had to shift to my 150 quart cooler to be able to hold the entire grain bill plus all the water to make my pre-boil volume.
For a thirty pound grist, the grain bed depth was 4 inches. I ran off 15 gallons of wort in 15 minutes, and it ran very clear after vorlauf.

I have no frame of reference for what are normal run-off times when doing no-sparge and batch sparges.
Can anyone elaborate for me? Denny, surely you know by heart how long to expect a batch to run off based on volume going to the kettle.

My guess is that so long as its not a stuck mash, grain bed depth has no effect on run-off speed for batch sparging.

Based on my current knowledge, the OP would do well to set up his rectangular cooler as a mash tun. It can't hurt to have both available, and as posted by others, it's a simple and cheap thing to do.
John Wilson
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Offline denny

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Re: Batch Sparge Theory
« Reply #12 on: January 14, 2011, 04:17:16 PM »
Denny, surely you know by heart how long to expect a batch to run off based on volume going to the kettle.

The one time I really timed it, it took 15 min. form the time I started the mash runoff til I finished the sparge runoff.  That includes the mash vorlauf, stirring in the sparge water, and sparge vorlauf.  That was for 8 gal. of wort in the kettle.
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Offline kerneldustjacket

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Re: Batch Sparge Theory
« Reply #13 on: January 14, 2011, 04:26:21 PM »
Denny, surely you know by heart how long to expect a batch to run off based on volume going to the kettle.

The one time I really timed it, it took 15 min. form the time I started the mash runoff til I finished the sparge runoff.  That includes the mash vorlauf, stirring in the sparge water, and sparge vorlauf.  That was for 8 gal. of wort in the kettle.

Mine was timed after vorlauf...and was non-stop with a fully-open 1/2" full port ball valve. Assuming that your pause to re-fill, stir, and vorlauf took half the 15 minutes, and that your volume was roughly half mine, the rates of actual wort drain-off were very similar; around 1 gallon a minute.
John Wilson
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Offline richardt

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Re: Batch Sparge Theory
« Reply #14 on: January 14, 2011, 04:31:00 PM »
Hmmm...  I'm listening to everyone's comments.  
And, yes, being a practical person, I probably will switch to a rectangular cooler.
My intuition still tells me that grain bed depth does make a difference.